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731.
Advances in seismics acquisition and processing and the widespread use of 4D seismics have made available reliable production‐induced subsurface deformation data in the form of overburden time‐shifts. Inversion of these data is now beginning to be used as an aid to the monitoring of a reservoir's effective stress. Past solutions to this inversion problem have relied upon analytic calculations for an unrealistically simplified subsurface, which can lead to uncertainties. To enhance the accuracy of this approach, a method based on transfer functions is proposed in which the function itself is calibrated using numerically generated overburden strain deformation calculated for a small select group of reference sources. This technique proves to be a good compromise between the faster but more accurate history match of the overburden strain using a geomechanical simulator and the slower, less accurate analytic method. Synthetic tests using a coupled geomechanical and fluid flow simulator for the South Arne field confirm the efficacy of the method. Application to measured time‐shifts from observed 4D seismics indicates compartmentalization in the Tor reservoir, more heterogeneity than is currently considered in the simulation model and moderate connectivity with the overlying Ekofisk formation. 相似文献
732.
An approach is developed to estimate pore‐pressure changes in a compacting chalk reservoir directly from time‐lapse seismic attributes. It is applied to data from the south‐east flank of the Valhall field. The time‐lapse seismic signal of the reservoir in this area is complex, despite the fact that saturation changes do not have an influence. This complexity reflects a combination of pressure depletion, compaction and stress re‐distribution throughout the reservoir and into the surrounding rocks. A simple relation is found to link the time‐lapse amplitude and time‐shift attributes to variations in the key controlling parameter of initial porosity. This relation is sufficient for an accurate estimation of pore‐pressure change in the inter‐well space. Although the time‐lapse seismic estimates mostly agree with reservoir simulation, unexplained mismatches are apparent at a small number of locations with lower porosities (less than 38%). The areas of difference between the observations and predictions suggest possibilities for simulation model updating or a better understanding of the physics of the reservoir. 相似文献
733.
利用Fortran语言编程实现了精密钟差文件的读取及信息筛选;在此基础上,利用滑动式Lagrange插值方法对精密钟差进行了加密,并对结果进行分析与讨论,得出了几点有益的结论。 相似文献
734.
735.
ABSTRACTA method based on workflow technology and Open Geospatial Consortium (OGC) specification is proposed to establish a universal workflow conceptual model in the network environment. In this paper, the soil fertility evaluation conceptual model was developed as an evaluation method of soil fertility by analyzing the GIS-based fertility evaluation method and extracting the dynamic variable to verify the feasibility model. This validation process involves determining the instantiation of the conceptual model. The proposed conceptual model achieved the following goals. All data acquisition and processing functions were packaged into an OGC-compliant service model; these service models were organized into a processing chain in a certain order on the workflow platform by Petri-Net; the fertility evaluation was realized on the workflow platform by calling the processing chain. Results showed that processing functions and data can be shared in the network environment, and the network workflow model can be realized by the workflow technology. The successful implementation of fertility evaluation proved the feasibility of the network-based universal workflow conceptual model. In addition, the flexibility of our modeling method is demonstrated by reconstructing the workflow model. 相似文献
736.
737.
Service accessibility and urban transportation choices are crucial in cities' endeavours for securing social equality and environmental sustainability. They are particularly relevant when the public service network is to be rationalized. In this paper we provide a practical example of comparing the impacts of current varying service allocation strategies on travel behaviour and the resulting carbon dioxide (CO2) emissions. We take libraries as a local public service to examine the CO2 emissions resulting from residents' library trips in the capital region of Finland. Our analyses are based on data on library use (library loan database, N = 420,000), accessibility (comparable models of travel-time by car, public transportation and non-motorized transport) and customer transport choices (survey, n = 584). Our results show that (1) 52% of library customers use a library that is accessible from their home with minimum CO2 emissions (the “climate-optimal” facility provider), (2) the remaining 48% that choose a non-optimal facility provider produce nearly 90% of the total CO2-emissions related to library customer flows and (3) the service allocation strategies of the different municipalities lead to markedly different CO2-emission patterns resulting from service usage. To conclude, sustainability measures (in our case the CO2 burden) provide useful information on the impact of a service network structure which may be used alongside economic rationales. 相似文献
738.
Sequential application of the single shift Normal Homogeneity Test (NHT) to the time series of Sahel rainfall revealed three clusters of discontinuities or breakpoints separating climatically stationary periods: 1933–1944, 1955–1974, and 1980–1989. At least one breakpoint was detected in 33 of the 55 series analyzed, while two breakpoints occurred in 12. The breakpoints of 1933–1944 marked the termination of spatially localized droughts in western Burkina Faso and southern Mali. Generally speaking, the Sahel drought that began in the late 1960s, persisted into 1998. However, abrupt positive shifts that occurred during the late 1980s restored mean annual rainfall to pre-drought levels at isolated locations. The stationarity of the periods between breakpoints suggests that the abrupt shifts are the dominant source of inhomogeneity in Sahel rainfall. Unlike the widely used climatic normal periods (CNPs), stationary periods are suitable for calculating various empirical indices for application in agriculture and rural water-resources planning in the area. The large number of breakpoints detected at different time periods suggests that Sahel rainfall series are prone to sudden transitions between quasi-stable climatic regimes; much like the onset, drought may terminate abruptly through a sudden shift in the mean annual rainfall. [Key words: Sahel, West Africa, drought, rainfall.] 相似文献
739.
Wenwen Li Chaowei Yang Chongjun Yang 《International journal of geographical information science》2013,27(8):1127-1147
The increased popularity of standards for geospatial interoperability has led to an increasing number of geospatial Web services (GWSs), such as Web Map Services (WMSs), becoming publicly available on the Internet. However, finding the services in a quick and precise fashion is still a challenge. Traditional methods collect the services through centralized registries, where services can be manually registered. But the metadata of the registered services cannot be updated timely. This paper addresses the above challenges by developing an effective crawler to discover and update the services in (1) proposing an accumulated term frequency (ATF)–based conditional probability model for prioritized crawling, (2) utilizing concurrent multi-threading technique, and (3) adopting an automatic mechanism to update the metadata of identified services. Experiments show that the proposed crawler achieves good performance in both crawling efficiency and results' coverage/liveliness. In addition, an interesting finding regarding the distribution pattern of WMSs is discussed. We expect this research to contribute to automatic GWS discovery over the large-scale and dynamic World Wide Web and the promotion of operational interoperable distributed geospatial services. 相似文献
740.
Peng Yue Wenli Yang Genong Yu Peisheng Zhao Jianya Gong 《International journal of geographical information science》2013,27(9):1139-1163
In a Web service‐based distributed environment, individual services must be chained together dynamically to solve a complex real world problem. The Semantic Web Service has shown promise for automatic chaining of Web services. This paper addresses semi‐automatic geospatial service chaining through Semantic Web Services‐based process planning. Process planning includes three phases: process modeling, process model instantiation and workflow execution. Ontologies and Artificial Intelligence (AI) planning methods are employed in process planning to help a user dynamically create an executable workflow for earth science applications. In particular, the approach was implemented in a common data and service environment enabled by interoperable standards from OGC and W3C. A case study of the chaining process for wildfire prediction illustrates the applicability of this approach. 相似文献